Aligned and axially loaded pig injector valve, threaded connection and method for connecting threaded members

ABSTRACT

A threaded connection comprising a first threaded member threadably connected with a second threaded member and an axial loading member. The first threaded member defines an opening for passage of the axial loading member therethrough, wherein the axial loading member protrudes from the first threaded member when in an extended position. The second threaded member has a loading surface defining a recess therein for receipt of the axial loading member when in the extended position such that the axial loading member bears on the loading surface and imparts an axial tensile force between the first and second threaded members. A method for connecting the members includes threading together the first and second threaded members, and passing the axial loading member through the opening defined by the first threaded member, so as to bear on the second threaded member within the recess, imparting the axial tensile force between the threaded members.

FIELD OF INVENTION

The present invention relates to a method and apparatus for connectingtwo threaded members, and in particular, to a method and apparatus foraxially loading the mated threads of a valve flange and a valve bodywhile maintaining alignment of the bolt holes of the flange on a tubularmember with the bolt holes of the valve flange.

BACKGROUND OF INVENTION

A typical pipeline valve is equipped with one or more flanges. Thepurpose of the flanges is to allow the connection of the valve toanother flanged valve, to a flanged pipe or to a flanged fitting. Toenable the flange of the valve to be attached to the mating valve of theapplications described above, the bolt holes on the mating flanges mustbe geometrically aligned.

In valve designs where it is necessary to attach the valve flange to avalve body by means of a screw thread, it is not always possible toensure that the valve flange can be fastened to the valve body such thatthe boltholes of the valve flange are in the correct geometricalalignment. It is normal to apply torque to the valve flange such that anaxial loading is applied through the mating threads in order to preventthe threaded connection from becoming loose. However, when the valveflange is screwed on tight to the valve body, the boltholes of the valveflange may not be correctly aligned.

One existing approach to the problem is to incorporate a disc typespring such that as the mating threads are screwed together, the discspring is compressed and this provides the axial loading on the matingthreads while allowing a limited rotation of the mating threadedconnection in order to bring the valve flange bolt holes into thecorrect alignment.

Another approach to this problem is to design a deformable feature intoeither the valve flange or the valve body such that as the valve flangeis screwed into the valve body, where the deformable feature imparts anaxial loading to the mating threaded connection while allowing a limitedamount of rotation of the mating threaded connection in order to bringthe valve flange bolt holes into the correct alignment.

In both of the previously described approaches, axial loading is appliedto the mating threads when the spring or deformable feature comes intoeffect. Therefore, the axial loading applied to the mating threads isaffected by the need to achieve geometrical alignment of the valveflange boltholes. Further, the resistance to rotation of the valveflange relative to the valve body is determined by the frictionalresistance of the mating faces and the mating threads.

What is needed is an apparatus for applying an axial load to the matedthreaded connection of a valve flange and valve body whilst permittinggeometrical alignment of the bolt holes in the valve flange andproviding non-frictional resistance to rotation, that overcomes theproblems in the existing art.

SUMMARY OF INVENTION

The present invention relates to a method for connecting two threadedmembers of which one or both have a flange, and in particular,connecting a valve fitting with a tubular member having an attachmentflange. In a preferred embodiment, the valve fitting is a pig injectionvalve for connection in a pipeline.

In one aspect, the invention comprises a method for connecting a firstthreaded member with a second threaded member, of which one or boththreaded members includes a flange, comprising the step of passing anaxial loading member through an opening defined by one of the twothreaded members, so as to bear on the other threaded member, impartingan axial tensile force between the two threaded members.

In another aspect, the invention comprises a method of attaching atubular member having an attachment flange defining a plurality of boltholes to a valve fitting having a longitudinal axis for connection witha tubular member having an attachment flange, the fitting comprising:

-   -   a valve body having an outlet, a threaded end and a loading        surface; and    -   a valve flange comprising a first threaded end for engaging the        valve body threaded end, a flange for engaging the tubular        member attachment flange, said flange defining a plurality of        bolt holes, and a plurality of axial loading members each        movable between a first position retracted away from the loading        surface and a second extended position protruding to bear on the        valve body loading surface to impart an axial tensile force        between the valve body and valve flange;        wherein the method comprises the steps of:    -   (a) threading the valve flange onto the valve body;    -   (b) rotating the valve flange until the bolt holes on the flange        of the valve flange are geometrically aligned with the bolt        holes on the attachment flange of the tubular member; and    -   (c) moving the axial loading member into its second extended        position so that it bears on the loading surface of the valve        body.

In another aspect, the invention may comprise a valve fitting having alongitudinal axis for connection with a tubular member having anattachment flange, the fitting comprising:

-   -   (a) a valve body having an outlet, a threaded end and a        circumferential loading surface at a substantially right angle        to the longitudinal axis of the fitting; and    -   (b) a valve flange comprising a first threaded end for engaging        the valve body threaded end, a flange for engaging the tubular        member attachment flange, and a plurality of axial loading        members each movable between a first position retracted away        from the loading surface and a second extended position        protruding to bear on the valve body loading surface to impart        an axial tensile force between the valve body and valve flange.

In another aspect, the invention may comprise a valve fitting apparatushaving a longitudinal axis for connection with a tubular member havingan attachment flange, the fitting comprising:

-   -   (a) a valve body having a threaded end defining an outlet, and a        loading surface; and    -   (b) a valve flange comprising a threaded end engaging the valve        body threaded end, a flange for engaging the tubular member        attachment flange, and an axial loading member movable between a        first position retracted away from the loading surface and a        second extended position protruding to bear on the valve body        loading surface to impart an axial tensile force between the        valve body and valve flange.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described by means of an exemplary embodimentas shown in the accompanying, simplified, diagrammatic, not to scaledrawings. In the drawings:

FIG. 1 is a cross sectional side view of one embodiment of the presentinvention.

FIG. 2 is a cross sectional perspective view of one embodiment of thepresent invention.

FIG. 3 is a diagrammatic depiction illustrating the alignment of thebolt holes of mating flanges of one embodiment of the present invention.

FIG. 4 is a diagrammatic depiction of the axial loading member of oneembodiment of the present invention.

DETAILED DESCRIPTION

As used herein, any reference to “a” or “an” element shall not beconstrued to mean ‘only one’ unless it is expressly stated to do so.

As used herein, a “pig” means a device that moves through the inside ofa pipeline for the purpose of cleaning, dimensioning, or inspecting.

The invention will now be described having reference to the accompanyingfigures. In a basic form, the invention may apply to any threadedconnection between two members, to resist uncoupling of the two membersor unwanted movement between the two members and to align the twomembers. In one embodiment, the invention has particular relevance tovalve fittings within pipelines, as described below.

As depicted in FIGS. 1 and 2, the apparatus comprises a valve fitting(10) having a valve flange (20) and a valve body (12). In a preferredembodiment, the valve fitting is a pig injection valve as shown in theFigures. Accordingly, the valve body (12) has an outlet at each endwhich are both threaded (16). The threaded outlets each attach to avalve flange (20). However, the valve body (12) may have any number ofthreaded outlets depending on the type of valve fitting. For example, a‘T’ valve fitting may have three threaded outlets, and a cross valvefitting may have four threaded outlets. The valve body (12) also has atleast one loading surface (18) used to axially load the threadedconnection between the valve body (12) and the valve flange (20) asdescribed below. In a preferred embodiment, the loading surface is acircumferential shoulder which is substantially at a right angle to thelongitudinal axis of the valve fitting.

The valve flange (20) comprises a flange (24), a threaded end (22) thatengages the threaded end of the valve body (12), and at least one axialloading member (26). Suitable seals such as O-rings may be providedbetween the valve flange (20) and the valve body (12) as is well knownin the art.

In a preferred embodiment, there are a plurality of axial loadingmembers. The axial loading member (26) is movable between a firstposition whereby it is retracted away from the loading surface when thevalve flange is connected to the valve body, and a second position whereit protrudes to bear upon the loading surface (18). In a preferredembodiment, the axial loading members are substantially parallel to thelongitudinal axis of the valve fitting and move along a parallel axis.

The flange (24) on the valve flange (20) defines a series of bolt holes(34) that correspond geometrically with bolt holes on the flange of thetubular member (44) to which the valve fitting (10) is being connected.FIG. 3 illustrates the required alignment of the connectors, or boltholes, in the flange of the tubular member (44) with those bolt holes inthe valve flange (20).

In one embodiment the axial loading member (26) is housed within apassage (32) in an abutment of the valve flange (20). The interiorsurface of the passage (32) and the exterior surface of the axialloading member (26) may be configured with complementary threads (notshown in the diagrams) so that the axial loading member (26) can bemoved into its second extended position by rotating it within thepassage (32). The axial loading member (26) may be a set screw, howeversuch other means as are commonly used to retract and extend members inthe art may be utilized.

In a preferred embodiment, the set screws (26) may have a tapered pointand the loading surface (18) on the valve body (12) defines a number ofrecesses (30) to receive the set screws (26) when extended into theirsecond extended position. It should be understood that a plurality ofaxial loading members, loading surfaces and recesses can be utilizedwith the present invention. Accordingly, when the set screws areextended and engaged in the recesses, it will be apparent that the setscrews impart an axial tensile force between the valve body (12) and thevalve flange (20). As well, the valve body and the valve flange cannotbe rotated relative to each other without shearing the set screws. Asused herein, an “axial tensile force” is a force which tends to separatethe valve body and the valve flange, along their longitudinal axes.

Once the threads of the valve flange (20) and the valve body (12) havebeen engaged, the axial loading member (26) is moved into its secondextended position so that it protrudes into the recess (30) and bears onthe loading surface (18). As torque is applied to the axial loadingmember (26), a resulting axial tensile force is applied between thevalve body (12) and the valve flange (20). In other words, the axialloading members impart a force tending to separate the valve body (12)and the valve flange (20). This results in an axial loading beingapplied through the mated threads of the valve flange (20) and the valvebody (12). Thus, unwanted loosening of the mated threads is prevented bythe extended axial loading member (26) and friction in the threadedconnection. Once the flange (24) is aligned with the pipeline flange,the threaded connection between the valve body and the valve flange canbe axially loaded without further rotation of the valve flange.

In a preferred embodiment, the axial loading member (26) comprises aconical point screw housed in a passage (32), and the use of a conicalshaped recess (30) in the loading surface (18). The end of the conicalpoint screw mates with the conically shaped recess (30) on the loadingsurface (18) ensuring that each axial loading member (26) contributes toaxial loading and also shear resistance to rotation. FIG. 4 is adiagrammatic depiction of a conical point screw suitable for use withthe present invention. A specified amount of torque may be applied toeach axial loading member (26) to attain an appropriate amount of axialloading.

The valve fitting (10) may be a ball valve, or such other suitable valvefitting as would be selected by one skilled in the art. As depicted inFIG. 2, the valve fitting may be suitable for use for inserting orextracting pigs from a pipeline, and may be a pig injector valve havingan aperture (42) and a sealing cap (not shown).

The valve fitting (10) may be constructed from any suitable materialincluding, without limitation, suitable metals or alloys thereof, orsuitable plastic or composite materials.

The use of the invention will now be described having reference to FIGS.1 and 2. The valve body (12) and the valve flange (20) are screwedtogether. The valve flange (20) is rotated until the bolt holes in theflange (24) are geometrically aligned with the bolt holes in theattachment flanges of the tubular member (44) that the valve fitting(10) is being attached to. One particularly effective method is tothread together the valve flange and the valve body until no furtherrotation is possible. The valve flange can then be reversed slightlyuntil the bolt holes are aligned. With a typical bolt pattern of apipeline attachment flange, this may be accomplished with less than a90° turn.

The set screws (26) are then rotated, extending them into their secondextended position whereby they bear upon the loading surface (18) of thevalve body (12). Sufficient torque is applied to the set screws (26) toaxially load the mated threads enough that the threads becomefrictionally engaged. The flange (24) on the valve flange (20) and theattachment flange on the tubular member (44) are then bolted together.Alternatively, the flanges may be bolted together before the axialloading members are extended into their second position. This process isrepeated if the valve fitting (10) has a second threaded end forattachment to a second tubular member.

As will be apparent to those skilled in the art, various modifications,adaptations and variations of the foregoing specific disclosure can bemade without departing from the scope of the invention claimed herein.The various features and elements of the described invention may becombined in a manner different from the combinations described orclaimed herein, without departing from the scope of the invention.

1. A method for connecting a first threaded member with a secondthreaded member, one or both of which include a flange, comprising: (a)threading together the first and second threaded members; (b) passing anaxial loading member through an opening defined by the first threadedmember, so as to bear on the second threaded member within a recessdefined by a loading surface of the second threaded member, imparting anaxial tensile force between the two threaded members.
 2. The method ofclaim 1 wherein the axial loading member is a set screw.
 3. The methodof claim 2 wherein the set screw engages the first threaded member in athreaded opening having a longitudinal axis substantially parallel to alongitudinal axis of the first threaded member.
 4. The method of claim 1wherein the axial loading member has a tapered end for receipt in therecess.
 5. The method of claim 1 wherein the recess is conical.
 6. Themethod of claim 5 wherein the axial loading member has a tapered end forreceipt in the recess.
 7. The method of claim 1 wherein the axialloading member is substantially parallel to a longitudinal axis of thefirst threaded member.
 8. The method of claim 6 wherein the axialloading member is substantially parallel to a longitudinal axis of thefirst threaded member.
 9. A threaded connection comprising: (a) an axialloading member movable between a first retracted position and a secondextended position; (b) a first threaded member defining an opening forpassage of the axial loading member therethrough, wherein the axialloading member protrudes from the first threaded member when in thesecond extended position; (c) a second threaded member threadablyconnected with the first threaded member, wherein the second threadedmember has a loading surface defining a recess therein for receipt ofthe axial loading member when in the second extended position such thatthe axial loading member bears on the loading surface and imparts anaxial tensile force between the first threaded member and the secondthreaded member.
 10. The threaded connection of claim 9 wherein theaxial loading member has a tapered end for receipt in the recess. 11.The threaded connection of claim 9 wherein the recess is conical. 12.The threaded connection of claim 11 wherein the axial loading member hasa tapered end for receipt in the recess.
 13. The threaded connection ofclaim 12 wherein the axial loading member is substantially parallel to alongitudinal axis of the first threaded member.
 14. The threadedconnection of claim 9 wherein the axial loading member comprises a setscrew.
 15. The threaded connection of claim 14 wherein the opening isthreaded.
 16. The threaded connection of claim 15 wherein the axialloading member is substantially parallel to a longitudinal axis of thefirst threaded member.